This invention relates to apparatus for generating a histogram of input values and to a method of binning input values so as to generate such a histogram.
The processing pipelines of digital cameras commonly make use of histograms to summarise the frequency distribution of parameters captured by pixels of the camera sensor such as exposure or colour channel parameters. A histogram divides the range of possible input values of a parameter into a series of bins, with each bin representing a count of the number of pixels having a parameter falling within the respective range of that bin. Such histograms can be used by the image processing algorithms of the pipeline in order to perform control functions of the camera such as auto-exposure, auto-focus and auto-white balance. A camera sensor will generally include many millions of pixels and the use of such histograms helps to provide a summary of the characteristics of a captured frame at a level of detail which is appropriate and manageable by pipeline algorithms.